122 SHIRO AKABORI 



We could not determine whether the amino acid corresponding to the small 

 peak was leucine or isoleucine. 



As is well known in synthetic organic chemistry, in the presence of a certain 

 catalyst, acetylene readily reacts with hydrogen cyanide to form acrylonitrile; 

 the presence of the latter substance in the fore-atmosphere is quite conceivable. 

 The formation of glutamine, glutamic acid, ornithine and arginine could thus 

 be formulated as shown in Fig. 8. 



Formation of Glutamic acid, OrnithinCj Arginine 



NH >- NH NH NH 



CH. CH2=CH— CN CH— CH2— CH2— CN >CH— CH2— CH2— CONH2->CH— CH2— CH2— COOH 



Glu 



CO HC = CH CO CO CO 



I -^ I ;2H2 1 , I 



HCN I I 



NH NH 



I NH2CN I 



CH-CH,-CH2-CH2— NH2 ^ CH— CH2-CH2-CH2— NH— C-NH2 



I I il 



CO CO NH 



1 Orn 1 Arg 



Fig. 



It 1 am aliowea to make a more extended speculation, I could formulate the 

 mechanism of the formation of lysine as shown in Fig. 8. The first step is a 

 cross-linked condensation of one molecule of acrolein with two polyglycine 

 chains, giving rise to a ^-hydroxy-aa'-diaminopimelic acid residue. This 

 hydroxydiaminopimeUc acid could have been reduced to diaminopimelic acid 

 which was shown by Dewey & Work [7] and also by B. D. Davis [8] to be the 

 precursor of lysine in Escherichia coli. It is very important that, according to 

 E. Work [9], diaminopimelic acid is widely distributed among various micro- 

 organisms. These findings might support the proposed mechanism on the 

 formation of lysine. 



Although I am afraid I went too far with my speculation, I would like to 

 emphasize that it seems not too difficult to test the theory on experimental bases. 

 Further work along this theory is now in progress in the Laboratory for Protein 

 Research of Osaka University. 



